1. Field of the Invention
The present invention relates to an improved adjustment/engagement device which can be applied to a rise-and-fall adjustment device in the forward portion of a seat cushion, an inclination adjustment device in the seat cushion, a tilt device in the seat cushion, or an adjustment/support device for a head-rest in a vehicle seat.
2. Description of the Prior Art
Conventionally, an adjustment/engagement device of this type is provided with an operation mechanism such as a screw mechanism, gear mechanism or cam mechanism and an operation lever mounted to the outside of a seat for operation of such operation mechanism. Such conventional adjustment/engagement device, however, is complicated in structure and also requires a large number of components due to the provision of the operation lever or the like. Further, since in operation loads applied to its members on its movable side are carried by the operation lever, the operation lever and its cooperative members must be formed strong and rigid and thus such prior art device is large in weight and expensive. In addition, as the movable-side member is operated indirectly by means of the operation lever, large operating loads are produced in the prior art device and, especially when the movable-side member comprises a forward frame portion of a seat cushion or an entire seat cushion, such prior art device can not be operated smoothly.